The present invention relates generally to disposable nozzles for mixing and dispensing a multi-component foam, and more particularly, to nozzles for mixing and dispensing two component foam systems using reduced chlorofluorocarbons (CFC), chlorofluorocarbons (CFC), hydrochlorofluorocarbons (HCFC), hydrofluorocarbons or water or any combination of the above as foaming agents.
The use of urethane and similar expandable foams has increased over the years for numerous applications. Urethane foams are well known as having desirable characteristics useful for many applications, such as insulation. Urethane foams are also well known for their compatibility with low cost blowing agents which allow such foams to be applied by way of pressurized containers as well as their natural adhesive qualities which allow such foams to bond excellently to any number of substrates. Typically, urethane foams are the reaction product of two individual components, one being a foaming agent and the other being a resin. These two individual components when reacted together, give the resultant foam various chemical compositions, each such composition having significant utility in a particular application. Thus, urethane foams may be specially formulated to provide a final foam which is rigid, semi-rigid or flexible.
Closed cell urethane foams are best used in building and structural insulation while open cell urethane foams are best used for packaging or non-insulating purposes. Regardless of the cell structure, the urethane foam is formed by mixing the two or more individual foam components together when the components exit their respective containers by way of individual supply tubes leading to a foam application gun. The components can be provided in small containers such as aerosol cans, containing up to 1 or 2 pounds of each component, or can be large cylinders, containing up to 1000 or more pounds of each component.
The foam component containers are connected to a dispensing tool or gun whereby each component is conveyed from the container by a distinct supply tube into the dispensing gun, the two or more components are mixed together in a disposable member and the reacted foam is applied through a nozzle of the gun. The dispensing gun typically includes an inlet assembly having tubes or other supply means from the foam component containers, a body portion having a dispensing trigger or other suitable mechanism to dispense the foam, and a nozzle assembly having an opening from which the foam exits. In operation of such dispensing guns, the separate foam components exit from their respective containers and enter a mixing chamber to form the final desired urethane foam. During mixing, the separate components are blended to form the urethane foam which then exits the spray nozzle at the outlet opening. Such foam dispensing guns and spray nozzles therefor are disclosed in assignee's patents, U.S. Pat. No. 3,784,110, U.S. Pat. No. 4,603,813 and U.S. Pat. No. 4,925,107. For the most part, these patents describe nozzles which are disposable and insertable into a foam dispensing gun body to establish an area where the separate foam components may be thoroughly mixed together before exiting the gun through the spray nozzle. Such nozzle assemblies are inexpensive and may be ejected or thrown away when the foam application is completed.
The urethane foam components used in these spray guns and nozzles therefor are maintained in their separate containers often in a pressurized state, using common foaming agents such as chlorofluorocarbons. Chlorofluorocarbons, or CFC's, are fully halogenated hydrocarbons which have been demonstrated as being detrimental to the ozone layer of the atmosphere. These liquids and gases provide excellent dispersal of liquids in aerosol applications because of the back pressure developed thereby, but nevertheless are detrimental to the environment. In recognition of this problem, federal regulations are now mandating a forced reduction by industry in the amounts of CFC and other related, atmosphere-damaging propellants used in aerosol applications. The overall goal of these regulations is to totally eliminate the use of these propellants in the aerosol application industry.
In order to comply with these environmental regulations, the industry is reducing the amount of CFC used as a propellant in aerosol applications. The industry is also utilizing water-blown systems wherein water is contained within one foam component and reacts with another foam component, typically an isocyanate, to form carbon dioxide which, as it expands, provides the frothing agent. However, water-blown and reduced CFC foam spraying systems do not always develop a proper or optimum back pressure required to propel the mixed foam out of the spraying nozzle of the gun onto the substrate in an even pattern. When the back pressure is insufficient, the foam tends to drip from the spray nozzle of the gun and when the back pressure is too great, the foam tends to exit the nozzle unevenly which results in the formation of a generally non-uniform pattern on the substrate.
The present invention overcomes the above disadvantages by providing an improved foam spraying nozzle for use in spraying foams with reduced CFC or with non-CFC foaming agents, the nozzle having an internal mixing chamber disposed between a nozzle portion and an inlet portion and wherein the nozzle portion includes a tip member having a generally cylindrical sidewall which is interrupted by an angular re-entrant portion in the form of a V-shaped notch, which nozzle configuration permits a generally uniform spray pattern without heavy spots or dripping. The nozzle tip may also be provided with an internal bore having two distinct diameters, wherein the diameters of the nozzle tip decrease as they approach the V-shaped re-entrant portion.
Accordingly, it is an object of the present invention to provide an improved, disposable spray nozzle for use on foam dispensing equipment in which the nozzle has a nozzle tip with an angular re-entrant portion.
It is another object of the present invention to provide a spray mixing nozzle for use on foam dispensing systems which utilize low CFC foaming agents in which the spray nozzle has an angular re-entrant portion at its nozzle tip which overcomes the spraying disadvantages associated with low back pressures.
It is a further object of the present invention to provide a foam dispensing gun for use with either non-CFC, CFC or reduced CFC foam systems in which the gun has a disposable spray nozzle having an inlet end, an outlet end, an intermediate internal mixing chamber disposed therebetween, the outlet end including an elongated nozzle extension, the nozzle extension having first and second diameters, the first diameter portion being disposed forwardly of the mixing chamber and the second diameter portion being disposed forwardly of the first diameter portion, the nozzle extension further having an expanded outlet opening in the form of an angular re-entrant portion which expanded opening modifies the flow of foam out of the nozzle to effect a desired deposition pattern of the same.
It is yet a further object of the present invention to provide a spray nozzle for foam dispensing systems in which the foaming agent is a reduced CFC and in which the spray nozzle has an elongated outlet passage having two internal foam passages, each passage having a distinct diameter leading up to a re-entrant portion, the upstream section having a greater diameter than the downstream section which increases the velocity of the exiting foam as it passes through the downstream section, the downstream nozzle section having an angular re-entrant portion which contains an angle of between approximately 40.degree. and approximately 120.degree., such that the expanded foam is sprayed out of the nozzle in a consistent, generally uniform application without the occurrence of "heavy" spots.
These and other objects of the present invention will become more readily apparent from a reading of the following detailed description taken in conjunction with the accompanying drawings wherein like reference numerals indicate like parts.